After purchasing other mice which were either too small or responded too slowly or were suspiciously lightweight, at last I have a good one. It's a reasonable size: 12cm x 6.5cm, important information not always provided by Amazon ! It feels solid and above all, it responds quickly and reacts quickly to clicks which feel precise. The central rotating wheel turns a bit noisily and roughly, but given the reasonable price, this is a minor niggle. Now I know why friends recommend a logitech mouse.